- Elevated circulating creatine kinase activity (HP:0003236): The activity of creatine kinase in the blood circulation is above the upper limit of normal. Evidence: PCS. Frequency: Occasional (HP:0040283). (PMID:17444505)
- Mitochondrial depletion (HP:0030059): An abnormal reduction in mitochondrial DNA content of cells. Evidence: IEA. (OMIM:611705)
- Myopathy (HP:0003198): A disorder of muscle unrelated to impairment of innervation or neuromuscular junction. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Difficulty climbing stairs (HP:0003551): Reduced ability to climb stairs. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Atrioventricular reentrant tachycardia (HP:0011717): Accessory pathway-related atrioventricular reentrant tachycardia (AVRT) involves an abnormal electrical conduction of the accessory pathway. The accessory pathway connecting impulses between the atrium and the ventricle can be seen at any site in the AV groove. Evidence: PCS. Frequency: 1/5. (PMID:17444505)
- Infantile onset (HP:0003593): Onset of signs or symptoms of disease between 28 days to one year of life. Evidence: TAS. Frequency: 3/5. (OMIM:611705)
- Motor delay (HP:0001270): A type of Developmental delay characterized by a delay in acquiring motor skills. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Arrhythmia (HP:0011675): Any cardiac rhythm other than the normal sinus rhythm. Such a rhythm may be either of sinus or ectopic origin and either regular or irregular. An arrhythmia may be due to a disturbance in impulse formation or conduction or both. Evidence: PCS. Frequency: 4/4. (PMID:17444505)
- Weakness of facial musculature (HP:0030319): Reduced strength of one or more muscles innervated by the facial nerve (the seventh cranial nerve). Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Severely reduced left ventricular ejection fraction (HP:0012666): A large reduction in the fraction of blood pumped from the left ventricle with each cardiac cycle. The normal range in adults is at over 50 percent, and a severe reduction is defined as less than 30 percent. Evidence: PCS. Frequency: 4/4. (PMID:17444505)
- Increased endomysial connective tissue (HP:0100297): An increased volume of the endomysium, which is a connective tissue sheath that surrounds each muscle fiber. Together, bundles of muscle fibers form a fasciculus, surrounded by another layer of connective tissue called the perimysium. Evidence: PCS. Frequency: 2/5. (PMID:17444505)
- Difficulty running (HP:0009046): Reduced ability to run. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Minicore myopathy (HP:0003789): Multiple small zones of sarcomeric disorganization and lack of oxidative activity (known as minicores) in muscle fibers. Evidence: PCS. Frequency: 3/5. (PMID:17444505)
- Sudden cardiac death (HP:0001645): The heart suddenly and unexpectedly stops beating resulting in death within a short time period (generally within 1 h of symptom onset). Evidence: PCS. Frequency: 4/5. (PMID:17444505)
- Neonatal onset (HP:0003623): Onset of signs or symptoms of disease within the first 28 days of life. Evidence: PCS. Frequency: 2/5. (PMID:17444505)
- Dilated cardiomyopathy (HP:0001644): Dilated cardiomyopathy (DCM) is defined by the presence of left ventricular dilatation and left ventricular systolic dysfunction in the absence of abnormal loading conditions (hypertension, valve disease) or coronary artery disease sufficient to cause global systolic impairment. Right ventricular dilation and dysfunction may be present but are not necessary for the diagnosis. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Generalized muscle weakness (HP:0003324): Generalized weakness or decreased strength of the muscles, affecting both distal and proximal musculature. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Centrally nucleated skeletal muscle fibers (HP:0003687): An abnormality in which the nuclei of sarcomeres take on an abnormally central localization (or in which this feature is found in an increased proportion of muscle cells). Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Scoliosis (HP:0002650): The presence of an abnormal lateral curvature of the spine. Evidence: PCS. Frequency: 1/5. (PMID:17444505)
- Joint contracture (HP:0034392): A limitation in the passive range of motion of a joint resulting from loss of elasticity in the periarticular tissues owing to structural changes of non-bony tissues, such as muscles, tendons, ligaments, joint capsules or skin. A contracture prevents movement of the associated body part. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Calf muscle hypertrophy (HP:0008981): Muscle hypertrophy affecting the calf muscles. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Ptosis (HP:0000508): The upper eyelid margin is positioned 3 mm or more lower than usual and covers the superior portion of the iris (objective); or, the upper lid margin obscures at least part of the pupil (subjective). Evidence: PCS. Frequency: 5/5. (PMID:17444505)
- Autosomal recessive inheritance (HP:0000007): A mode of inheritance that is observed for traits related to a gene encoded on one of the autosomes (i.e., the human chromosomes 1-22) in which a trait manifests in individuals with two pathogenic alleles, either homozygotes (two copies of the same mutant allele) or compound heterozygotes (whereby each copy of a gene has a distinct mutant allele). Evidence: PCS. (PMID:17444505)
- Congestive heart failure (HP:0001635): The presence of an abnormality of cardiac function that is responsible for the failure of the heart to pump blood at a rate that is commensurate with the needs of the tissues or a state in which abnormally elevated filling pressures are required for the heart to do so. Heart failure is frequently related to a defect in myocardial contraction. Evidence: PCS. Frequency: 1/4. (PMID:17444505)
- Atrioventricular block (HP:0001678): Delayed or lack of conduction of atrial depolarizations through the atrioventricular node to the ventricles. Evidence: PCS. Frequency: 1/5. (PMID:17444505)
- Increased variability in muscle fiber diameter (HP:0003557): An abnormally high degree of muscle fiber size variation. This phenotypic feature can be observed upon muscle biopsy. Evidence: PCS. Frequency: 5/5. (PMID:17444505)
These phenotypes are associated with the disease early-onset myopathy with fatal cardiomyopathy (OMIM:611705).